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Venezuelan President Hugo Chavez said Friday that the U.S. man arrested and accused of being a possible "mercenary" told authorities he was a former Marine.

The man was detained this month while illegally trying to cross the border from Colombia into Venezuela, according to the president.

"The man has military training and is refusing to provide information. That's suspicious," Chavez said, according to a government statement.

Little is known about the detainee, including his name. Chavez has said that the U.S. citizen "had all the appearances of a mercenary."

He had a passport with stamps from recent years in Iraq, Afghanistan, Jordan, Germany, Great Britain, Colombia and the Dominican Republic, the president said. Chavez said the man carried a notebook and had tried to destroy some pages of it when he was arrested.

U.S. officials are operating on the assumption that Chavez's forces have someone in custody, a U.S. government source told CNN on Friday. The source said U.S. officials have reached out to the Venezuelan government on the matter, but haven't received information.

Chavez, who is running for reelection, has repeatedly accused U.S. officials and members of Venezuela's opposition of plotting to destabilize the country's government.